This invention relates to a system which utilizes selected combinations of diffraction gratings as a means for forming indicia on tags or like labeling material for use in marking price, inventory number, routing instructions, and the like in merchandising operations while simultaneously providing a tag or label which can be effectively read at different angles. A number of different systems and arrangements have been used over the years to enable machine reading of such tags or labels, two of the most recent being the bar code arrangement and the bullseye arrangement.
A review of prior art in the area of indicia marking systems shows that in U.S. Pat. No. 3,312,955, entitled "System for Recording and Retrieving Digital Information", to R. L. Lamberts, et al., there is disclosed a system which is first used to convert a combination of electrical signals representative of an item of information into a grating pattern on an optical material and is then later used to decode the pattern. Multiple positions of the pattern are created by orientating the grating at different angles during the construction of the grating pattern.
An additional prior art device of interest is disclosed in U.S. Pat. No. 3,314,052, entitled "Light Modulation System", to A. W. Lohmann wherein there is shown and described a light modulation system which system operates upon the angular orientation of a diffraction grating to impart information.
In U.S. Pat. No. 3,525,566, entitled "Projection Devices and Materials Therefor", to G. Altman there is disclosed an optical projector for imaging a subject in terms of reflected light using an array of optical elements, which array is comprised of a plurality of reflex reflectors, and a focusing system for controlling the illuminating light directed to the subject and for imaging the light reflected by the array.
Several other patents of interest in the reflex reflector art are U.S. Pat. No. 2,326,634, entitled "Reflex Light Reflector" to M. C. Gebhard et. al.; U.S. Pat. No. 2,407,680, entitled "Reflex Light Reflector", to P. V. Palmquist; U.S. Pat. No. 2,440,584, entitled "Lenticular Reflex Reflector Sheet And Method Of Making The Same", to H. Heltzer et. al., and U.S. Pat. No. 2,713,286, entitled "Reflex Light Reflectors and Glass Bead Elements Thereof", to N. W. Taylor.
While the above mentioned prior art suggests various ways and means for utilizing diffraction gratings and reflex reflectors for carrying information, it is desirable that certain improvements be made in the prior art devices so as to provide a more commercially utilizable device.